All the lore and narrative events from the old system will be returning - albeit some (like Hazel) will be significantly changed, as their old events would no longer make sense :)
I was hoping to get it all in for v0.20.0, but it's proving to be slightly more complicated than expected so it might (emphasis on might) be pushed to 0.20.1. Hopefully not, though.
The rehab centre unfortunately won't be making a return, but you will be able to hang out and chat with the Boss Girls - and the Goons, once I get a certain thing in place - so you will have that social aspect again.
Specific locations like the Glades and the Training Course (totally not an excuse to indulge my inner love of tree villages, I swear) will also be making a return. Some will have a narrative purpose, and some will help boost your combat abilities.
All of the above will be in by 0.20.1 by the latest :)